What is it called when you shorten a phrase like madd?

When you shorten a phrase like "mad" to "madd," it's often referred to as "slang" or "informal language." This type of modification can also be considered a form of "abbreviation" or "contraction," where syllables are dropped or altered for ease of pronunciation or to convey a specific cultural meaning. Additionally, in some contexts, it may be categorized under "phonetic spelling" or "creative spelling."